A fat or oil containing diacylglycerol at a high concentration is known to have physiological effects such as suppression of an increase in blood triglyceride (neutral fat) level after meal and a small accumulation amount in the body (see Patent Documents 1 and 2, for example). On the other hand, diacylglycerol has a melting point higher than that of triacylglycerol and hence is liable to crystallize at low temperature, and crystals precipitated are hard to dissolve even if returning to room temperature.
As a method of suppressing crystallization of a fat or oil to provide a clear fat or oil, there has been known a method involving removing components having a high melting point in advance by wintering. For the fat or oil containing diacylglycerol at a high concentration, there has been reported a method involving adding an emulsifier as a separation aid during wintering and performing solid-liquid separation of crystals precipitated (Patent Document 3).